Treatment of artificial materials



Patented May 12,1942

UNITED STATES IPATENTAIOFFIICE' TREATMENT OF ARTIFICIAL MATERIALS 'David James Hadley and Thomas Jackson, Spondon, near Derby, England, assignors to Celanese Corporation of America, a corporation of Delaware No Drawing.

Application May 8, 1940, Serial No.

333,936. In Great Britain May 23, 1939 (01. s-1s2) i ticular materials, provided, of course, that the e 2 Claims.

This invention relates to the treatment of.

artificial materials, and more particularly to solvents,'swe1ling agents orlatent solvents, in,

the absence of tension sufilcient to stretch the materials,- serves to increase their extensibility.

The selection of the agents to be employed in this process is a matter of great importance and is determined by a number of factors involving elaborate research. The most important con-' sideration, which weighs very heavilywlth the manufacturer, is that of reproducibility or control of results, and this is a particularly important matter when dealing with'textile fabrics and like materials, since quite small variations in physical characteristics, especially extensibility, occurring over the length of such materials are shown up very clearly in fabrics formed therefrom, e. g. by the faults which arise from uneven tension during the fabric-forming operation. The over-all efficiency of the agents,

their toxicity, and economic factors generally also come into consideration,

We have now found that methyl, ethyl, and n and i-propyl formates, methyl acetate, methyl propionate and propylene chloride are highly satisfactory agents to employ for the purpose of increasing the extensibility of textile materials and the like having'a basis of an organic derivative of cellulose. Of these agents, the formates and methyl acetate, although not latent solvents for organic derivatives of cellulose, are yet surprisingly satisfactory in their influence on the extensibility of the materials and they possess the great merit of low toxicity. Further, these particular agents permit good control of the efiects produced. Methyl propionate and propylene chloride are" even more advantageous since it is found that they give advantageous retemperature of treatment is maintained constant.

According to the invention, therefore, artificial filaments, threads, yarns, fabrics, ribbons and the like made of or containing an organic erivativefof cellulose are subjected, in the abs nce of tension sufficient to stretch them, to the action of methyl formate, ethyl formate, n-propyl formate, i-propyl formate, methyl acetate, methyl propionate or propylene chloride.

Preferably, thetreatment is carried out while the filaments or other materials are under notension or under only a slight tension so that they aresubstantially free to shrink under the influence of the treatment agent. If the agents are applied while the materials are underrelatively high tension, the. tension should subsequently be reduced or removed so that the materials are allowed to shrink while still under the influence of the agents.

The treatment agents may be employed singly or in admixture with each other. Suitable dilu ents, for use more particularly with the methyl,

ethyl and nand i-propyl formates and methyl acetate, are, for example, glycol, glycerol and other hydroxy compounds which are substantially without action on the materials. Preferably, however, water-immiscible liquids are used as diluents, examples of which are benzene, toluene, xylene and other cyclic hydrocarbons, benzine, petroleum ether, kerosene and other aliphatic hydrocarbons, carbon tetrachloride, perchlorethylene and other chlorinated or halogenated compounds which are inert or substantiallyinert towards the cellulose derivatives. Again, relatively high boiling diluents, e. g. tetrahydronaphthalene and decahydronaphthalene, may'be employed.

The particular treatment agent, the concentration in which it is employed, and the temperature of working will depend upon the particular cellulose derivative which is present in the filaments or other materials to be treated,-

upon the physical characteristics of those materials and upon the degree of modification of the physical characteristics which is desired. Prefsults in the absence of any diluent. In other words, these two agents can be employed with effective control of the process with any parerably, the shrinkage effected does not exceed about 2.0 or 25% and it is generally most advantageous to effect a shrinkage 'of 10 to 15%; Shrinkage maybe restricted by suitably modi fying the treatment medium, as regards composition, concentration and/or temperature, and/or by treating the materials while they are under suflicient tension to prevent more than the desired shrinkage, the tension being maintained so long as the materials remain under the influence of the'treatment agent.

When treating materials having a basis of ace tone-soluble cellulose acetate, it is found that a satisfactory increase in extensibility can be se-,

greatest importance whenapplied to filaments,

threads, yarns, fabrics, ribbons and the like con-- taining or derived from high tenacity wet-spun materials or materials which have been stretched. to 200% or more of their original length in hot water or wet steam or in a medium containing an organicsolvent or swelling agent. -It will be understood, however, that the invention is not limited to the treatment of these materials,

but is applicable generally to organic derivative of cellulose materials the extensibility of which it is desired to increase. It has further been found that the treatment agents according to the present invention impart to staple fibres,

' particularly such as have-been formed by cut-- ting operations, a crinkled or crimped effect, which greatly enhances their spinning qualities.

Reference has been made above to materials having a basis of acetone-soluble cellulose acetate and the invention is of the greatest importance in connection with the treatment-of such' materials. However, materials made from other cellulose acetates or other esters of cellulose such as, for example, cellulose formate, propionate and butyrate and mixed esters, e. g. cellulose acetoto secure by Letters Patent is:

propionate and acetobutyrate; and also from I cellulose ethers, e. 3. methyl, ethyl and benzyl cellulose or from cellulose ether-esters, may be treated.

The following examples tion:

' Example 1 Dry-spun cellulose acetate yarn, which has been stretched in wet steam to 1000% of its original length, is immersed for ten minutes at 15 C.

illustrate the invenin hank form in a bath of 76% ethyl formate and 26% kerosene (percentage of volume), and

is allowed to'' shrink freely; The yarn is then increased.

washed with a low-boiling petroleum ether and dried in a current of warm air. The product is found to be uniformly shrunk and to have an improved extensibility.

Example 2 Dry-spun cellulose acetate yarn, which has been stretched in wet steam to 1000% of its original length, is immersed for ten minutes at 20 C. in hank form in a bath 'of methyl propionate and is allowed to shrink freely. The yarn is then further treated as in Example 1, and is found 'to possess similar characteristics to those of the product of Example 1.

Example 3 Dry-spun cellulose acetate yarn, which has been stretched in wet steam to 1000% of its original length is immersed for ten minutes at 76 C. in hank form in a bath of propylene chloride and allowed to shrink freely. After subsequent treatment as described in Example 1 the product is found to be uniformly shrunk and to have an improved extensibility.

Having described our invention, what we desire 1. Process for increasing the extensibility of artificial filamentary, materials made of or containing an organic derivative of cellulose, which comprises subjecting such filamentary materials which have been stretched in the presence of wet steam to 1000% of their original length to increase their' tenacity, to immersion for ten minutes at 15 C. in a bath containing '76% of an alkyl formate containing 2 to 4 carbon atoms in the molecule, in the absence of tension sufficient to stretch'said filamentary material's,whe reby said filamentary materials are shrunk by 10 to 15% of their length'a-nd their extensibility is 2. Process for increasing the extensibility of artificialfilamentary materials made of or containing cellulose acetate, which comprises subjecting such filamentary materials which have been stretched in the presence of wet steam to 1000% of their original length to increase their tenacity, to immersion for ten minutes at.15 C.

in a bath containing 76% of an alkyl formate containing 2 to 4 carbon atoms in the molecule,

in the absence of tension sufllcient to stretch said filamentary materials, whereby said filamentary materials are shrunk by 10 to 15% of their length and their extensibility is increased.

DAV I JAMES HADLEY. THOMAS JACKSON. 

